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Shape-memory alloy
Shape memory alloy(KIOKALLOY) excels in high-strength, corrosion resistance
KIOKALLOY, a Ni-Ti alloy, is superior for various reasons such as its strength and corrosion resistance. KIOKALLOY has been born out of Daido’s abundance of experience in working with special steel and high-purifying materials through original processes such as our melting furnace and vacuum arc furnace.
Features
- It can be set at a wide range of “recovery temperature”. （10℃～100℃）
- Its corrosion resistance is the same as titanium and titanium alloy.
- Its tensile strength is about 150kgf/mm2.
- Its super elasticity effect means that large distortions are easily corrected. Up to 8% of its shape can be recovered in the temperature zone beyond the shape recovery temperature.
Applications
| Shape-memory effect | Super-elasticity effect |
| Pipe joint（radioactive waste transport pipe） | Wire (brassiere, corset, drool bib for baby, frame of hat) |
| Dental root （inserted into the bone and fixed） | Frame of glasses |
| Electrical connector（Utilization of temperature up of inferior contact point) | Teeth-straightening(crownwork, arch wire) |
| Automatic closing mechanism of window | Catheter lead wire for introducing X-ray contrast medium (follow flexibly in vessel) |
| Air conditioner sensor flap | Rehabilitation apparatus for forming |
| Spring cellar | |
| Antifreezing valve (turn the faucet on lowering temperature) | |
| Fan clutch (stop operation at low temperature) | |
| Temperature alarm (alternative bimetal) | |
| Medical implant (expanding vessel) |
Chemical composition and shape-recovery temperature
| Item | Ni | Ti | Co | Cu | Shape-recovery temperature |
|
Ni-Ti alloy (KIOKALLOY-R) |
54～56 | Residual Bal. | - | - | 20～100℃ |
|
Ni-Ti-Co alloy (KIOKALLOY-S) |
53～55 | Residual Bal. | 1～3 | - | -30～30℃ |
|
Ni-Ti-Cu alloy (KIOKALLOY-T) |
47～50 | Residual Bal. | - | 5～9 | 40～70℃ |
- Shape-recovery temperature varies depending on forming and heat treatment conditions.
Mechanical properties
| Item | Ni-Ti alloy | Ni-Ti-Co alloy | Ni-Ti-Cu alloy | |
| Martensitic phase |
Tensile strength MPa (kgf/mm2) |
1175～1370 (120～140) |
1370～1570 (140～160) |
1175～1765 (120～180) |
|
Yield strength MPa (kgf/mm2) |
～196 (～20) |
～294 (～30) |
68～98 (7～10) |
|
| Elongation % | ～50 | ～50 | ～20 | |
|
Horizontal modulus of elasticity MPa (kgf/mm2) |
7845～9800 (800～1000) |
9800～13730 (1000～1400) |
0～4900 (0～500) |
|
| Austenitic phase |
Tensile strength MPa (kgf/mm2) |
1075～1175 (110～120) |
1275～1370 (130～140) |
1175～1765 (120～180) |
|
Yield strength MPa (kgf/mm2) |
390～785 (40～80) |
490～980 (50～100) |
390～785 (40～80) |
|
| Elongation % | ～20 | ～20 | ～20 | |
|
Tensile strength MPa (kgf/mm2) |
17650～21575 (1800～2200) |
19600～24500 (2000～2500) |
19615～27460 (2000～2800) |
|
- Mechanical properties vary depending on heat treatment conditions and service temperatures.
Comparison of physical properties
| Metal |
Density (g/cm3) |
Melting point (℃) |
Linear expansion coefficient (×10-6/K) |
Specific heat (J/(kg・K)) |
Thermal conductivity (W/m/℃) |
Electric resistance (Ωm) |
|
Ni-Ti （Austenitic phase） |
6.5 | 1250 ～1280 | 10 | 440 | 12.1 | 80～100 |
|
Ni-Ti-Co （Austenitic phase） |
6.5 | 1250 ～1280 | - | 470 | 12.7 | - |
|
Ni-Ti-Cu （Austenitic phase） |
6.4 | 1250 ～1280 | - | 460 | 13.5 | - |
| Titanium | 4.5 | 1668 | 8.4 | 520 | 17.1 | 55 |
| Nickel | 8.9 | 1453 | 15 | 460 | 92.0 | 9.5 |
| Iron | 7.9 | 1530 | 12 | 460 | 62.8 | 9.7 |
| SUS304 | 7.7 | 1400 ～1420 | 17 | 500 | 16.3 | 72 |
| Copper | 8.89 | 1083 | 17 | 380 | 385.0 | 1.724 |
- Physical properties, except for density and melting point of Ni-Ti alloy vary depending on temperature.
